**Question:** What is the difference between using `ref` and `reactive` in Vue 3? **Answer:** In Vue 3, both `ref` and `reactive` are used to create reactive data, but they differ in usage and context: - **`ref`** - Used to wrap basic types (e.g., `string`, `number`, `boolean`) or objects into reactive references. - Values must be accessed via `.value` (in `setup()` functions), but can be directly used in templates (Vue automatically unwraps them). - Example: ```js const count = ref(0); console.log(count.value); // 0 count.value++; // Updates the actual value ``` - **`reactive`** - Specifically for creating reactive proxies for object types (e.g., plain objects, arrays). - Implements deep reactivity via ES6 Proxy. - Cannot be used for basic types, and proxies entire objects without `.value`. - Example: ```js const state = reactive({ name: 'Alice', age: 25 }); console.log(state.name); // Alice state.age = 26; // Updates all nested properties ``` **Key Differences:** - **Data Type:** - `ref` handles basic types (e.g., numbers, strings). - `reactive` is for objects/arrays, requiring full proxying. - **Template Usage:** - `ref` is automatically unwrapped in templates, so `{{ count }}` works directly. - `reactive` objects require explicit unwrapping with `toRefs` when destructured. **Best Practices:** - Use `ref` for raw values (e.g., numbers, strings). - Use `reactive` for objects/arrays to enable deep reactivity. - `reactive` objects are "deeply reactive" by default, while `ref` wraps objects internally (e.g., `ref({})` is equivalent to `ref(reactive({}))`). **Recommendation:** Choose `ref` for general-purpose use in Vue Composition APIs due to its broader applicability. --- This translation maintains technical accuracy while ensuring clarity and professional tone. The structure adheres to Vue's documentation style, emphasizing distinctions between the two APIs.